Control of electric motors.



No. 66l,97|.- Patented Nov. 20, I900. F. W. GARRETT. CONTROL OFELECTRICMOTORS.

(Application filed Mar. 26, 1900.) (No'ModeL) 3 Sheets-Sheet l.

INVENTOB WI TNESSES jh 5 AIM QM,

M ATTORNEY N0. 66l,97|. v Patented Nov. 20, I900.-

' F. W. GARRETT.

CONTROL OF ELECTRIC MOTORS.

(Application filed Mar. 26, 1900.)

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Posifian 61 T I I WITNESSES: INVENTUR \m ATTORNEY.

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Patented Nov. 20, I900.

7 F. W. GARRETT. CONTROL OF ELEOTBIC MOTORS.

(Application mm In. 26; 1900.

s shun-sheet 3.

(No Model.)

1 5 5 .M u n w W m ATTORNEY.

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UNITED STATES PATENT OFFICE.

FRANK WV. GARRETT, OE JOHNSTOXVN, PENNSYLVANIA, ASSIGNOR TO THE LORAINSTEEL COMPANY, OF PENNSYLVANIA.

CONTROL OF ELECTRIC NIQTORS.

SPECIFICATION forming part of Letters Patent No. 661,971. dated November20, 1900.

Application filed March 26, 1900. Ecrial No. 10,151. No model.)

To (tZZ whom, it may concern:

Be it known that I, FRANK W. GARRETT, of Johnstown, in the county ofCambria and State of Pennsylvania, have invented a new and usefulImprovement in the Control of Electric Motors, of which the following isa full, clear, and exact description, reference being had to theaccompanying drawings, which form a part of this specification.

My invention has relation to the control of electric motors, andalthough not limited thereto is especially applicable to electricrailwaymotors. On many roads the motorcars are now provided with four motorsand with a controller having two interconnected drums each of which hascontacts and connections for controlling the circuit relations of onegroup of motors and for changing them from series to parallel relationand vice versa.

My invention is especially applicable to equipments or systems of thisgeneral character, although it may be used with three or more groups ofmotors as well as with two.

The object of my invention is to provide means for controlling motorsarranged as above stated in which the motors of each group are changedfrom series to multiple relation by a series of intermediate steps of acharacter to gradually accelerate and control their speed Without injurythereto, without the interposition of useless resistance, and without atany time entirely opening the circuit therethrough. v

Generally considered, my invention consists in a method ofseries-parallel control applied to a plurality of motors operated ingroups, preferably pairs, in which certain of the intermediate circuitchanges or steps are effected in one group of motors before the similarchanges or steps are effected in the other group or groups, the circuitin one group or groups remaining unbroken, while that of the other groupis opened to effect the desired changes. In this mannersome of themotors are at all times during the change from series to parallel actingto propel the car.

My invention also consists in a method of series parallel controlpossessing certain novel steps and combinations of steps, all ashereinafter described, and pointed out in the appended claims.

In the accompanying drawings, which illustrate my invention, Figure l isa diagram showing a controller developement and circuit arrangementsuitable for the practice of my invention. Fig. 2 is a graphicrepresentation of the motor-circuits in the several positions of thecontroller-drums; and Figs. 3, 4:,and 5 are planular sections of thecontrollerdrums,showing the relative positions of their contacts atcertain positions of the drums.

In the figures, M, M M and M indicate four electric motors, whosearmatnres are designated, respectively, as A, A A and A" and theirfield-coils F, F F and F. T indicates the connection to the trolley orsupply side of the circuit. G wherever seen indicates a groundconnection. 0 S designate the canopy-switches; E B, a fuse-box; L A, alightningarrester, and C C a choke-coil. These parts are of any usual.character and form no part of my invention.

C O represent in developement the two controller-drums, B o O is theblow-out coil therefor, and R S the reversing-switch.

R B designate artificial resistance-boxes for connection in circuit withthe motors in starting from or approaching a position of rest.

The drums C C in so far as their mechanical arrangement is concerned areof a wellknown type, being intergeared with each other in any well-knownor usual manner to move in unison by the operation of a single lever orhandle.

Each drum 0 O carries six groups of contacts, the individual contacts ofeach group being electrically connected with each other, while theseveral groups are electrically disconnected. The contacts of the firstgroup on each drum are marked 0 to c, inclusive; those of the secondgroup, a to 0 inclusive; those of the third group, o to c, inclusive;those of the fourth group, to 0 inclusive; those of the fifth group, 0to 0 inclusive, and those of the sixth group,- 0 to e inclusive. \Vhilethe number of contacts is the the contacts c, 0 0 c c and a on the drum0 are longer than the corresponding contacts on the drum C", in that onthe drum 0 these contacts terminate on or slightly beyond the indicatedposition 5, whereas on the drum 0 they extend to a point slightly beyondthe dotted line indicating the position 5 It will also be noticed thatthe contacts c e 0 c 0 c", 0 0 0 and 0 on the drum C are longer than thecorresponding contacts on the drum 0, being extended farther to theleft, so that while on the drum 0 these contacts are first engaged whenthe drum is turned to the position 6 on the drum G they are firstengaged at the position 5 The contact -fingers which cooperate with thecontacts of the drum 0 are designated by the numbers 10 to 22,inclusive, while the fingers which cooperate with the contacts 01' the drum C are designated by the reference characters 10 to 22, inclusive.

The reversing-switch R S is of well-known type and need not bedescribed, being shown only for the purpose of completing the electricalconnections. In tracing the circuits hereinafterit will be assumed thattheir series of contact-fingers are engaging the contacts on the dottedline marked ahead and designated by .232 &c., to Contact-fingers 10, 11,and 12 are electrically connected to the resistance-box R to connect incircuit, re-

spectively, a decreasing amount of the resistance therein, and fingers10, 11, and 12 are. similarly connected to the resistai'ice-box R.Finger 12 is also connected to one terminal 01' the field-coil F andfinger 12 is similarly connected to one terminal of the field-coil F.Finger 13 is electrically connected to linger 14, and the latter isconnected to one terminal of the field-coil F. Finger 13 is connected tofinger 1 1 and the latter to one terminal of the field-coil F Finger isconnected to one side oi the field-coil F and finger 15 to thecorresponding side of field-coil F". Fingers 10 and l6 are respectivelyconnected to armatures A" and A through the reversingswitch, and thereturn connections from said armatures through said switch are made,respectively, with the fingers 1t) and 19. Fingers 17 and 17 arerespectively connected to lield coils F and F Fingers l8 and 18 arerespectively connected to armatures A and A the return connections alsothrough said switch being to the fingers 21 and 21, respec tively.Finger 21 is connected to finger and linger 21 to finger 20. Fingers 22and 22 are connected in multiple with the blowout coil 13 o C, which isconnected with the trolley or supply side of the main circuit. L is alead grounded as indicated and to which resistance-boxes R and R areconnected. The first group of contacts of each drum C C is grounded onthe shaft thereof.

From the above description of the connections it will be seen that thedrum 0 controls motors M and M, while the drum G controls the motors Mand M, and that the two drums are electrically connected in multiple.

The operation is as follows: Starting from a position of rest, with thecontroller-drums in their first positions, the current from the trolleypasses through the blow-out coil and to the lingers 22 22 of the drumsin multiple. Inasmuch as the circuit through the contacts of one drum issubstantially the same as the circuit through the other drum and its twomotors in all except a few positions, it will be suificient except as tothose positions to trace one circuit. From the finger 22 the circuit isthrough contacts c and e linger 21 to finger 23 of the reversingswitch,contacts 00 x finger 25, to and through armature A, finger to finger 2b,to linger 18, contacts 0 0 finger 1.), linger 31, contacts e .2 finger35, to and through armatu re A to finger 32, contacts ,2 .2, finger 34;,finger 16, contacts c c, linger l7, field F, finger 14-, contacts c c",finger 15, field F", through resistance-box R to ground. In thisposition, therefore,the current passes through each pair of motors andthe resistance-box Iherelor in series. In position 2 the circuit is thesame, except that linger 10 engages contact c, and therebyshort-circuits a portion of the resistance, and in position theengagement of finger 11 with contact c short-circuits a further sectionof the resistance. In position 4-. the engagement of the linger 12 withthe contact c short-circuits the entire resistance. In position the onlychange which is effected is that the finger l5 bridges the contacts 0and 0 and thereby shortcireuits the field F, a similar short-circuit offield F taking place by the bridging of the fingers 15 and itsCOII'GSPOINIIIIL," contacts. In position a? the lingers 1st and 15 losetheir engagement with contacts c and 0, thereby cutting out the field F.Positions t and lare not notch or running positions, but occurmomentarily in passing from notch position 1 to notch position 5. Inposition 5 linger 13 engages the contact 0 and the circuit is throughthe two fields in multiple, the armature connections and circuitsremaining as before. A similar multiple connection of the fields F F isof course efiected. In position 5 the connections controlled by the drumC remain the same as in position 5; but owing to the fact that thecontacts c, c, a, 0 c and c of the drum (1 are shorter than thecorresponding contacts of the drum 0, as above described, the circuit isentirely opened through the motors M M". (See position 5 of Fig. 2;also, Fig. At position 5 the connections controlled by drum C stillremain the same as at position 5; but on the drum C the fingers 1%,15,16, 17,1S,1.'), 20, 21, and 22 engage, respectively, the contacts c c 00 ,0 ,0 e 0 and 0 thereby restoring the series connection of the licldsF F and connecting the artnatures A A in multiple. The circuit throughthe motors M M" is therefore as follows: to finger 22, to contacts 0 0and finger 21. Here the current divides, one part passing from finger 21to finger 27 of the reversing-switch, contacts .2 a finger 29, armatureA, finger 28, contacts ,2" .2, finger 30, finger 18, contacts 0 e finger17, field F finger 14:, contacts 0 0 finger field F finger 12, contact0, to ground. The other part of the current passes from finger 21 tofinger contacts 0 0 finger 19, finger of the reversi-ng-switch, contacts2' .2 finger 37, armature A, finger 36, contacts 5 5 finger 38 to finger1t), contact c to contact where its path unites withthat of the firstbranch described. At position 5 the connect-ions controlled by drum 0remain as in position 5; but the fingers of the drum C entirely loseengagement with the contacts of the drum 0', and thereby open thecircuit through the motors M and M (See position 5 Fig. 2; also, Fig.5.) When position 6 is reached, the connections controlled by drum 0remain the same as in po sition 5 but the fingers 12 and 14 to 22, inelusive, of the drum 0' are engaged, respectively, with the contacts 0 00 c 0 c e 0 0 and 0 This restores the series connection of the fields FF and connects the armatures A A in multiple, the circuit being similarto that traced in position 5 that is to say, the current divides betweenfingers 21 and 20, one part passing by way of finger 21 and thereversing-switch to and through armature A, thence back through saidswitch to the finger 18 and contacts 0* o while the other part passes byway of finger 20 contacts 0 e finger-19, and the reversingswitch,through armature A thence back through said switch to finger 16, tocontacts c 0 where the two paths unite, and the cu rrent passes inseries through fields F by way of finger c field F, finger 1e, contacts0 c finger 15, field F finger 12, and contact c to ground. Positions 5,5 and 5 are not notch positions; but position 6 is a notch position. Inposition (5 the fingers 16, 20, and 21 and 16, 20, and 21 have lostengagement with the respective contacts c c and 0 which breaks thecircuits to armatures A and A*, the other connections remaining as inposition 6. At position fingers 13 and 13 engage their respectivecontacts c, and thereby short-circuit the fields A and A". At position 6the fingers 14 and 15 and let 15 leave the contacts 0 c and thereby cutout the fields A A. Positions 6, 6 and 6 are not notch positions. Theelements of the motors are now in condition for connection in fullmultiple, and this is effected at position 7 by the engagement of thecontacts c, e o o and 0 by the corresponding fingers of each drum.\Vithout tracing out the circuits in full at this time it will bereadily seen that the current at each drum will divide between thefingers l9 and 21 or 19 and 21, one part going through thereversing-switch by a path similar to that before traced througharmature A or A, thence back to finger 18 or 18, contacts c 0 finger 17or 17, field F or F contact 0, to ground, and the other part through thereversingswitch, armature A or A, back to finger 16 or 10, to contacts cc, finger 15 or 15, to field l or 1 to finger 13 or 13, to contact 0, toground.

From the foregoing description it will be seen that while as to some ofits broad features my method of control is similar to the method andinvolves some of the steps described and claimed in the patents to\Vells H. liamlcn, Nos. UTEQOSS and ($415,089, and

Frank A. Merrick, Nos. 6%,116 and 615,117,

it provides for the lirsttime, in so far as 1 am aware, a system ofseries-parallel control for a plurality of motors in which artificialresistance is not employed after the series position and in which at notime are all the m0- tors cut out of circuit. I do not wish, therefore,to be limited to the use of the particular apparatus which 1 have shown,as various types of controllers might be devised to carry out my saidmethod, nor do I wish to be limited to the particular combination ofsteps which 1 have herein illustrated and described, since it is obviousthat the feature of effecting certain circuit changes in one pair ofmotors while the circuit in the other pair or pairs is kept intact maybe applied with advantage in connection with systems of control which asa whole differ from that herein described.

Having thus described my invention, what I claim, and desire to secureby Letters Patout, is-

1. The method of controlling a plurality of electric motors arranged ingroups,which coir sist-s in effecting certain circuit changes in onegroup of motors whereby the relations of the motors or motor elements inthat group are changed with respect to each other and during suchchanges keeping the circuit through the other group or groups unbroken.

2. The method of controlling a plurality of electric motors arranged ingroups by gradually changing the motors of each group from series toparallel relation through a series of steps, some of which are effectedin one group of motors in advance of the corresponding changes in theother group or groups and while the latter are actively in circuit.

3. The method of controlling a plurality of motors connected in parallelgroups, which consists in changing the motors of each group from seriesto parallel relation by circuit changes therein, some of which areeffected in one group before they are effected in the other group orgroups and without opening the circuit of the latter.

t. The method of controlling a plurality of electric motors whichconsists in starting them from a position of rest with their fields andarmatures connected in series, then connecting their fields in multiple,then connecting their armatures in multiple and their fields in series,and finally connecting the motors as a Whole in multiple, those circuitchanges which effect the multiple connections of the armatures alonebeing effected in some of the motors in advance of such changes in theremaining motors and without opening the circuit therethrough.

5. The method of controllinga plurality of electric motors in groups orpairs connected in multiple with each other, which consists in startingthem from a position of rest with the armatures and field-coils of eachgroup or pair connected in series, then connecting the fields inmultiple, then connecting the armatures in multiple and the fields inseries,

and finally connecting the motors of each pair or group in multiple, themultiple connection of the armatures alone being effected in one groupor pair in advance of the other group or groups and Without opening thecircuit of the latter.

6. In a series-parallel system of control for a plurality of electricmotors, the method of connecting their armatures in multiple whichconsists in first breaking the circuit through some of the motors whilemaintaining a circuit through the remaining motors, then connecting thearmatures of the first-named motors in multiple and reconnecting them incircuit, and then effecting like changes in the remaining motors.

7. In a series-parallel system of control for a plurality of electricmotors, the method of connecting the armatures in multiple whichconsists in first connecting the armatnres of one group or pair'inmultiple without breaking the circuit through the remaining motors, andthen effecting a like connection in the remaining motors Whilemaintaininga circuitthrough the first group or pair, substantially asdescribed.

tie-197i 8. The method of controlling a plurality of electric motorsconnected in parallel groups, which consists in starting with the motorsof each group connected in series, then connecting the field-coils ofeach group in parallel, then cutting out one group, and reconnectingthem in circuit with their armatures in parallel and theirfields inseries, then making similar changes in the other group or groups, andfinally connecting the motors of each group wholly in parallel with eachother.

9. The method of controlling a plurality of electric motors connected inparallel groups, which consists in starting with the motors of eachgroup connected in series, then connecting certain elements of themotors of each group in parallel with the remaining elements still inseries, then by further changes in each group, connecting those elementsin parallel which were before in series and those elements in serieswhich were before in parallel, and finally connecting the motors of eachgroup wholly in parallel.

10. The method of controlling a plurality of electric motors connectedin parallel groups of two motors each, which consists in first removingthe field-coils of one motor of each group and reconnecting them inparallel with the field-coils of the other motor of the group, thencutting out each group successively, and reconnecting it in circuit withits armatures in parallel and its field-coil in series, and thenconnecting the motors of each group wholly in parallel with each other.

In testimony whereof I have affixed my signature in presence of twowitnesses.

FRANK W. GARRETT.

Witnesses:

R. M. EVANS, BLANOHE M. SMITH.

